vmw_diff_memcpy(9)

💅 vmw_diff_memcpy(9) — the Kernel API Manual ✨

okay so bestie, welcome to vmw_diff_memcpy(9) from the Kernel API Manual, and trust me when I say this little function is doing the most for blit tracking 🎀

🌸 NAME 🌸

vmw_diff_memcpy — a memcpy that also builds you a cute lil bounding box of everything it just modified 💖

✨ SYNOPSIS ✨

void vmw_diff_memcpy (struct vmw_diff_cpy *diff , u8 *dest , const u8
*src , size_t n );

🦋 ARGUMENTS 🦋

• diff — the struct vmw_diff_cpy that keeps track of the modified bounding box. it's literally the main character here 👑
• dest — where the copy lands, i.e. the destination 🎯
• src — where the bytes come from, i.e. the source 🫶
• n — how many bytes we're copying, no cap 🔢

💜 DESCRIPTION 💜

So here's the tea ☕ — if you want this function to correctly track the modified content, you gotta pre-load some stuff first, bestie, and there is no skipping it:

• the field diff->line must be pre-loaded with the current line number 🧚
• the field diff->line_offset must be pre-loaded with the line offset in bytes where the copy starts 📏
• and finally the field diff->cpp needs to be preloaded with the number of bytes per unit in the horizontal direction of the area we're examining ✨

and yeah, cpp is typically bytes per pixel — iconic of it honestly. why do we need it? because it tells us the needed granularity of the difference computing operations, and that's just facts 💀

bestie heads up: a higher cpp generally leads to faster execution but at the cost of bounding box width precision. so like, speed vs. precision, the classic tradeoff, pick your fighter ⚔️

🔥 SEE ALSO 🔥

• Kernel file ./drivers/gpu/drm/vmwgfx/vmwgfx_blit.c 📁
• vmw_find_first_diff(9)
• vmw_find_last_diff(9)
• vmw_memcpy(9)
• vmw_adjust_rect(9)
• struct vmw_bo_blit_line_data(9)
• vmw_bo_cpu_blit_line(9)
• vmw_bo_cpu_blit(9)

okay that's the whole page bestie, you ate that 🍓 this lil gem lives over in ./drivers/gpu/drm/vmwgfx, dated October 2026, and it's filed under vmw_diff_memcpy(9) — periodt 💅✨🌈